20311891 has 2 divisors, whose sum is σ = 20311892. Its totient is φ = 20311890.

The previous prime is 20311883. The next prime is 20311901. The reversal of 20311891 is 19811302.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20311891 - 2³ = 20311883 is a prime.

It is not a weakly prime, because it can be changed into another prime (20311801) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10155945 + 10155946.

It is an arithmetic number, because the mean of its divisors is an integer number (10155946).

Almost surely, 2^20311891 is an apocalyptic number.

20311891 is a deficient number, since it is larger than the sum of its proper divisors (1).

20311891 is an equidigital number, since it uses as much as digits as its factorization.

20311891 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 432, while the sum is 25.

The square root of 20311891 is about 4506.8715313397. The cubic root of 20311891 is about 272.8454939349.

The spelling of 20311891 in words is "twenty million, three hundred eleven thousand, eight hundred ninety-one".